The aim of the so-called precrystallization step in the conventional production of chocolate or chocolate-like masses is the generation of a sufficiently large number of fat crystal germs which, after the forming or molding of the mass, initiate the further solidifying crystallization in the subsequent cooling process. It is of particular importance therein that the germ crystals generated in the precrystallization step are present in a desired stable crystal modification. For the cocoa butter fat system these are the so-called βV and βVI crystal modifications in which the principal triglycerides of the cocoa butter (SOS, POP, SOP, S=stearin, O=olein, P=palmitin) are present arranged in a triclinic crystal lattice. So-called unstable modifications are the γ-crystal structures (amorphous), α-crystal structures (hexagonal), and βIV-crystal structures (orthorhombic). The modification of the crystal germs determinatively affects the formation of additional crystals during the cooling and solidification of the molded, precrystallized masses.
To the extent that the germ crystals consist predominantly of unstable modifications, a predominantly unstable rigid end product results as a consequence after the termination of the cooling process in the production process. During storage unstable crystals are converted into stable modifications even at low storage temperatures since they are thermodynamically more stable and therefore of lower energy. Crystals of unstable modifications have a less dense hardening structure. This, and the diffusion process running during the modification conversion, require that, in particular, fat portions with a low melting point are “transported” to the surface of the chocolate product and there form a crystal film, so-called bloom. This bloom causes the graying of the chocolate surface and thereby a clear affect on the quality of the chocolate. If sufficiently stable crystal germs are generated during the precrystallization, no bloom formation is shown during storage.
Along with the generation of crystal germs which are as stable as possible during the precrystallization, it is in particular also a goal to minimize as much as possible the total amount of the generated crystal germs without endangering the effective precrystallization quality, since this leads to a reduced viscosity during molding or forming of the precrystallized mass and thereby to processing advantages. Low mass viscosities are a prerequisite for the uniform forming, for example, in production of coatings for filled products (production of hollow bodies) in order to insure uniform wall thicknesses.
In traditional precrystallization processes ca. 0.5 to 2% relative to the total fat mass are solidified in the form of germ crystals. Depending on the origin (provenance) of the cocoa butter as well as due to the physical/chemical interaction between the triglycerides (fats) and other components of the formulation (in particular emulsifiers), the crystallization kinetics can run differently. This necessarily leads, with the largely determined dwelltime in the industrial process, to sharp deviations in the precrystallization state, which has an effect on the quality of the product. In the traditional precrystallization technology it is attempted to realize as optimal a precrystallization as possible by variation of a step-wise management of the temperature. This requires on the one hand much empirical experience and on the other hand the adjustability is problematic even for small deviations in temperature in the precrystallization process (for example, +/−1° C.).
The so-called temperature meter process serves to monitor the precrystallization quality in the traditional process monitoring (offline). In this measurement process a small sample volume, which is drawn from the precrystallization apparatus at precrystallization temperature, is introduced into a sample tube, at whose center a temperature sensor in installed. The sample tube is cooled under defined temperature conditions (water bath) and the temperature curve measured in the sample. The temperature curve determined reflects the curve of the solidifying crystallization in the sample. The “inclination toward crystallization” can be identified in this manner with a certain temperature curve (as a function of time) due to the precrystallization release of heat of the sample. Depending on the form of a temperature curve of this type one skilled in the art can make a classification of “over, under, and well temperature-controlled”.
Traditional processes or apparatuses for the precrystallization of chocolates work according to the principle of a step-wise temperature control. This means that the chocolate mass arriving at temperatures >45° C. in a temperature controller (precrystallizer) as a rule is easily precooled in three temperature control zones (temperature control zone 1: ca. 30° C.), then supercooled (temperature control zone 2:25 to 27° C.), and finally warmed up to a processing temperature (temperature control zone 3: 28 to 31° C.). The exit temperature from traditional precrystallizers (temperature controllers) is between 28 and 31° C., in rare cases slightly over 31° C. If a mass is pretemperature-controlled as described, then the direct analysis of the germ crystals arising, said analysis being performed by means of a so-called direct DSC (Differential Scanning Calorimetry) measurement on the mass drawn after the crystallizer, shows a typical crystal modification spectrum. In the case of cocoa butter as a continuous fatty phase, the predominant share of the crystal germs consists of βV-crystals (50-70%), followed by βIV-crystals (20-40%), as well as in part of remnants of α-crystals (ca. 10%). As a rule a predominant share of βV-crystals guarantees that the solidifying crystallization will achieve a sufficient quality of structure to insure bloom stability and other marks of quality (for example, crisp breaking behavior, soft melt). Nonetheless, in the case of traditional crystallized chocolate masses, in particular when fatty shares with a low melting point (for example, milk fat or nut oil) are also contained, quality deficiencies frequently occur due to the formation of bloom. Partially the bloom first shows itself after 2-3 months storage (possibly even longer). Chocolates with bloom cannot be sold or lead to customer returns.
From WO 98/30108 a process for the precrystallization of chocolates is known in which the melted product is seeded directly with a crystal powder. As will be described further below, the seeding by means of crystal powders is associated with numerous disadvantages in practice.